btrfs: reada: reduce additional fs_info->reada_lock in reada_find_zone

We can avoid additional locking-acquirment and one pair of
kref_get/put by combine two condition.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index 49b3fb7..7448080 100644 (file)
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -260,18 +260,14 @@ static struct reada_zone *reada_find_zone(struct btrfs_fs_info *fs_info,
        spin_lock(&fs_info->reada_lock);
        ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
                                     logical >> PAGE_CACHE_SHIFT, 1);
-       if (ret == 1)
+       if (ret == 1 && logical >= zone->start && logical <= zone->end) {
                kref_get(&zone->refcnt);
-       spin_unlock(&fs_info->reada_lock);
-
-       if (ret == 1) {
-               if (logical >= zone->start && logical <= zone->end)
-                       return zone;
-               spin_lock(&fs_info->reada_lock);
-               kref_put(&zone->refcnt, reada_zone_release);
                spin_unlock(&fs_info->reada_lock);
+               return zone;
        }
 
+       spin_unlock(&fs_info->reada_lock);
+
        cache = btrfs_lookup_block_group(fs_info, logical);
        if (!cache)
                return NULL;